On Mon, Oct 03, 2011 at 08:17:05AM -0500, Anthony Liguori wrote: > On 10/02/2011 07:14 AM, Michael S. Tsirkin wrote: > >On Sun, Oct 02, 2011 at 02:01:10PM +0200, Avi Kivity wrote: > >>>Hmm, not entirely virtio specific, some devices use stX macros to do the > >>>conversion. E.g. stw_be_phys and stl_le_phys are used in several > >>>places. > >> > >>These are fine - explicit endianness. > > > >Right. So changing these to e.g. stl_dma and assuming > >LE is default seems like a step backwards. > > We're generalizing too much. > > In general, the device model doesn't need atomic access functions. > That's because device model RAM access is not coherent with CPU RAM > access. > > Virtio is a very, very special case. virtio requires coherent RAM > access.
Right, but it should only need that for the actual rings in the virtio core. I was expecting that those would remain as direct physical memory accesses - precisely because virtio is special - rather than accesses through any kind of DMA interface. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson